Throughout Amazon's 25-year history, there have been multiple rumblings of workers trying to unionize, but to no success.
With record-breaking sales numbers and newly doubled shipping speeds, however, momentum to organize has picked up among some of Amazon's more than 650,000 worldwide employees.
Three big unions are among those talking to Amazon workers — the Teamsters, the United Food & Commercial Workers Union and the Retail, Wholesale and Department Store Union. Recent worker protests point to organizing efforts.
On Prime Day in July, a handful of Amazon workers at a fulfillment center in Shakopee, Minnesota, went on strike. It was the first strike by U.S. workers during the company's annual sales events that started five years ago, and one of several protests in the U.S. in the past year.
The protests were organized by the Awood Center, an East African worker advocate group that's backed in part by the Teamsters and the Service Employees International Union, along with local labor groups like the Minneapolis Regional Labor Federation.
"The people who participated in today's event are mainly outside organizers who are uninformed about what it's really like to work inside an Amazon fulfillment center," Amazon spokesperson Rachael Lighty said at the time. "With only 15 employees who participated from this site, that tells me that our employees truly do believe that they are working in a safe and innovative workplace."
Last year, Amazon led the industry by raising its minimum wage to $15 an hour, and it's known for generous benefits. Its Career Choice program pays up to 95% of tuition for associates studying high-demand fields. And last month, Amazon pledged $700 million to retrain a third of its U.S. workforce by 2025 to move to more advanced jobs.
"We're already offering what unions are asking, which is industry leading pay, great benefits and a safe and innovative workplace," Lighty said.
In the video, an animated man wearing a yellow safety vest says, "We are not anti-union, but we are not neutral either. We do not believe unions are in the best interest of our customers or shareholders or most importantly, our associates."
It goes on to give tips to managers for spotting union activity.
"Make it a point to regularly talk to associates in the break room. This will help protect you from accusations that you were only in the break room to spy on pro union associates," the video says.
Amazon said the training video has not been used since last year, and it was in compliance with the National Labor Relations Act.
Amazon is also recruiting employee relations managers whose duties include having "significant experience in handling union organizing activities" and "responding to union activity."
On Twitter, a group of Amazon employees known as Fulfillment Center Ambassadors actively tweet about how much they love working at Amazon, often in response to threads about poor treatment of Amazon workers. Some FC ambassadors have tweeted anti-union messages like "Unions are thieves" and "Union protection makes it hard for employers to discipline, terminate or promote."
The last official unionizing attempt at Amazon was in 2013, when maintenance and repair technicians in Delaware filed with the NLRB. The union was voted down 21 to 6.
But whether Amazon workers are currently signing union authorization cards is a closely guarded secret.
"The only thing that you can do on an organizing campaign is operate under surprise," said UFCW president Marc Perrone. "If an employer knows that you're signing cards and doing things like that, they will come after them tooth and toenail."
Company spokesperson Lighty said: "Amazon respects the rights of our employees, and we have a zero tolerance policy on retaliation for employees raising their concerns."
After Amazon bought Whole Foods in 2017, workers there also showed signs of organizing. Last September, The Wall Street Journal reported that a group of Whole Foods workers sent an email to workers at most of the 490 stores urging them to back a unionization drive.
In Europe, where unions have a stronger foothold, Amazon workers also remain nonunion. But workers there have been more active, staging protests during sales days for years. In Germany, more than 2,000 people participated in Prime Day protests in at least seven locations last month.
Amazon workers CNBC talked to expressed opinions on both sides of the debate.
"I like the direct communication with my team," said Corissa Lueken, senior operations manager at the Shakopee Amazon Fulfillment Center. "I think this is why we're so successful is we can we can pivot. We need to make sure that we're always keeping a focus on our customers — both internally and externally as well. And I don't think that really works with our union kind of environment, but that's just my personal opinion."
Others were more positive about unionizing.
"Everybody coming together kind of showed them we are trying to be one, and it's not like we don't want to work here, but we just want change," said Amazon worker Sahro Sharif, who was among the pickets outside the Shakopee Fulfillment Center.